Intramedullary rods are widely used in orthopedic surgery to fix certain broken bones and to maintain the bone fragments in the proper alignment during healing and to provide strength during the convalescence of the patient.
One such intramedullary rod with which the present invention is most useful is described by Zindrick and Sohngen in patent application Ser. No. 230,563, filed Aug. 10, 1988. This intramedullary rod is referred to generally herein, but reference is made to said patent application for a more complete and detailed description.
It is necessary, in most instances, to affix the intramedullary rod to one or both fragments of the bone using bone screws or other fasteners. Thus, intramedullary rods are provided with a plurality of apertures therethrough for receiving screws or fasteners of various configurations. Fixation of the intramedullary rod requires that these apertures be precisely located, that passages be drilled through the compact cortical tissue and the cancellous tissue of the bone and that the fastener screws be secured in the bone tissue through the apertures in the intramedullary rod to fix the intramedullary rod in the proper relationship with the bone fragments.
X-ray viewers or x-ray films are widely used to display the relationship of the bone fragments, intramedullary rod and, after installation, the fastener screws. Many such viewing devices and systems are available. The present invention is useful with targeting devices which are specifically designed to guide the installation of distal bone screws through apertures in the intramedullary rod, but may be used with any intramedullary rod installation device which includes an external support assembly which carries or is adapted to support and position such targeting devices.
The present invention is specifically designed and most advantageously used in connection with the targeting device described in U.S. Pat. No. 4,881,535, Nov. 21, 1989, to Sohngen, but may be used with other external support assembly type devices for installing intramedullary rods.